scholarly journals Using X-ray, K-edge densitometry in spent fuel characterization

1998 ◽  
Author(s):  
T. Jensen ◽  
T. Aljundi ◽  
J.N. Gray
Keyword(s):  
Spent Fuel ◽  
X Ray ◽  
Fuel Characterization

scholarly journals Strengthening the SSTC NRS Scientific and Technical Potential through Participation in the IAEA Coordinated Research Projects

2021 ◽  
pp. 5-13
Author(s):  
Yu. Balashevska ◽  
D. Gumenyuk ◽  
Iu. Ovdiienko ◽  
O. Pecherytsia ◽  
I. Shevchenko ◽  
...  
Keyword(s):  
Best Practices ◽  
Safety Assessment ◽  
Radiation Safety ◽  
Research Projects ◽  
Spent Fuel ◽  
Research Activities ◽  
Technical Potential ◽  
Technical Issues ◽  
Fuel Characterization ◽  
Definition Of

The State Scientific and Technical Center for Nuclear and Radiation Safety (SSTC NRS), a Ukrainian enterprise with a 29-year experience in the area of scientific and technical support to the national nuclear regulator (SNRIU), has been actively involved in international research activities. Participation in the IAEA coordinated research activities is among the SSTC NRS priorities. In the period of 2018–2020, the IAEA accepted four SSTC NRS proposals for participation in respective Coordinated Research Projects (CRPs). These CRPs address scientific and technical issues in different areas such as: 1) performance of probabilistic safety assessment for multi-unit/multi-reactor sites; 2) use of dose projection tools to ensure preparedness and response to nuclear and radiological emergencies; 3) phenomena related to in-vessel melt retention; 4) spent fuel characterization. This article presents a brief overview of the abovementioned projects with definition of scientific contributions by the SSTC NRS (participation in benchmarks, development of methodological documents on implementing research stages and of IAEA technical documents (TECDOC) for demonstration of best practices and results of research carried out by international teams).

Applications of Nuclear Data Covariances to Criticality Safety and Spent Fuel Characterization

2014 ◽  
Vol 118 ◽  
pp. 341-345 ◽  
Author(s):  
M.L. Williams ◽  
G. Ilas ◽  
W.J. Marshall ◽  
B.T. Rearden
Keyword(s):  
Nuclear Data ◽  
Spent Fuel ◽  
Fuel Characterization ◽  
Criticality Safety

Nondestructive, Energy-Dispersive, X-Ray Fluorescence an Analysis of Actinide Stream Concentrations from Reprocessed Nuclear Fuel

1979 ◽  
Vol 23 ◽  
pp. 163-176
Author(s):  
D. C. Camp ◽  
W. D. Ruhter
Keyword(s):  
Nuclear Fuel ◽  
Nitrate Solution ◽  
Fission Products ◽  
Analytical Techniques ◽  
Fluorescence Analysis ◽  
Energy Dispersive ◽  
Light Water Reactors ◽  
Spent Fuel ◽  
X Ray ◽  
Water Reactors

In the event that nuclear fuel from light water reactors (LWR) is reprocessed to reclaim the uranium or plutonium, several analytical techniques will be used for product accountability. Generally, the isotopic content of both the plutonium and uranium in the reprocessed product will have to be accurately determined. One plan for the reprocessing of LWR spent fuel incorporates the following scheme. After separation from both the fission products and transplutonium actinides (including neptunium and americium), part of the uranium and all of the plutonium in a nitrate solution will merge together to form a coprocessed stream. This solution will be concentrated by evaporation and sent to a hold tank for accountability. Input concentrations into the hold tank could be up to 350 g U/ℓ and nearly 50 g Pu/ℓ. The variation to be expected in these concentrations is not known. The remaining uranium fraction will be further purified and sent to a separate storage tank. Its expected stream concentration will be about 60 g U/ℓ. These two relatively high actinide stream concentrations can be monitored rapidly, quantitatively, and nondestructively using the technique of energy-dispersive x-ray fluorescence analysis(XRFA).

Neodymium Incorporation in Zirconolite-Based Glass-Ceramics

2000 ◽  
Vol 663 ◽  
Author(s):  
P. Loiseau ◽  
D. Caurant ◽  
N. Baffier ◽  
C. Fillet
Keyword(s):  
Heat Treatment ◽  
Glass Ceramics ◽  
Fission Products ◽  
Treatment Temperature ◽  
Spent Fuel ◽  
X Ray Diffraction ◽  
Parent Glass ◽  
X Ray ◽  
Spin Resonance

ABSTRACTThe investigations on enhanced reprocessing of nuclear spent fuel, and notably on separating the long-lived minor actinides, such as Am and Cm, from the other fission products have led to the development of highly durable specific matrices such as glass-ceramics for their immobilization. This study deals with the characterization of zirconolite (CaZrTi2O7) based glass-ceramics synthesized by devitrification of an aluminosilicate parent glass. Trivalent actinide ions were simulated by neodymium, which is a paramagnetic local probe. Glass-ceramics with Nd2O3 contents ranging from 0 to 10 weight % were prepared by heat treatment of a parent glass at two different growth temperatures: 1050° and 1200°C. X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and electron spin resonance (ESR) measurements clearly indicate that Nd3+ ions are partly incorporated in zirconolite crystals formed in the bulk of the glass-ceramic samples. The amount of neodymium in the crystalline phase was estimated using ESR results and was found to decrease with increasing either heat treatment temperature or total Nd2O3 content.

Behavior of UO2 in the RBMK-1000 Spent Fuel under Oxidizing Conditions

2004 ◽  
Vol 824 ◽  
Author(s):  
A. B. Kolyadin ◽  
V. Ya. Mishin ◽  
K. Ya. Mishin ◽  
A. S. Aloy ◽  
T. I. Koltsova
Keyword(s):  
Thermal Oxidation ◽  
Spent Nuclear Fuel ◽  
Oxidation Process ◽  
Spent Fuel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dry Storage ◽  
Different Temperatures ◽  
Xrd Techniques

AbstractThe oxidation of UO2–type spent nuclear fuel (SNF) in gaseousmedia was studied at different temperatures and oxygen contents using gravimetric and powder X-ray diffraction (XRD) techniques. The aim of the study was to determine the mechanism(s) of thermal-oxidation alteration of SNF during long-term dry storage. The samples used in the experiments were chips of RBMK-1000 fuel rods.Oxidation of UO2with a mean burn-up of 10.7 and 19.73 MW d/kg in humid air was observed at a temperature as low as 150°C. At 200°C nearly all of the UO2was transformed into U3O8 between 3500-4000 hours. In a humid nitrogen environment containing of 0.05-1.3 vol. % oxygen at 300°C, the UO2 completely transformed to U3O8 between 2500-3000 hours. Oxidation of UO2in samples with small amounts of jacket damage (e.g., <0.04 MM2)ll progresses more slowly and after â3000 hours the oxygen-to-uranium ratio was 2.56.Stabilization of the oxidation process was not observed in the fuel samples upto an O/U ratio of 2.4, which may be attributed to the smallburn-up of the fuel under investigation.

scholarly journals Direct Measurement of Plutonium in Spent Fuel with X-ray Fluoresence

2011 ◽  
Author(s):  
Catherine E Romano ◽  
Allisa Stafford ◽  
Alexander A Solodov ◽  
Michael H Ehinger
Keyword(s):  
Direct Measurement ◽  
Spent Fuel ◽  
X Ray

scholarly journals Chemical and elemental mapping of spent nuclear fuel sections by soft X-ray spectromicroscopy

2022 ◽  
Vol 29 (1) ◽  
Author(s):  
Alexander Scott Ditter ◽  
Danil E. Smiles ◽  
Daniel Lussier ◽  
Alison B. Altman ◽  
Mukesh Bachhav ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Focused Ion Beam ◽  
Spent Nuclear Fuel ◽  
Ion Beam ◽  
Atom Probe ◽  
Chemical Information ◽  
Spent Fuel ◽  
X Ray ◽  
Trivalent State ◽  
Micrometer Scale

Soft X-ray spectromicroscopy at the O K-edge, U N 4,5-edges and Ce M 4,5-edges has been performed on focused ion beam sections of spent nuclear fuel for the first time, yielding chemical information on the sub-micrometer scale. To analyze these data, a modification to non-negative matrix factorization (NMF) was developed, in which the data are no longer required to be non-negative, but the non-negativity of the spectral components and fit coefficients is largely preserved. The modified NMF method was utilized at the O K-edge to distinguish between two components, one present in the bulk of the sample similar to UO2 and one present at the interface of the sample which is a hyperstoichiometric UO2+x species. The species maps are consistent with a model of a thin layer of UO2+x over the entire sample, which is likely explained by oxidation after focused ion beam (FIB) sectioning. In addition to the uranium oxide bulk of the sample, Ce measurements were also performed to investigate the oxidation state of that fission product, which is the subject of considerable interest. Analysis of the Ce spectra shows that Ce is in a predominantly trivalent state, with a possible contribution from tetravalent Ce. Atom probe analysis was performed to provide confirmation of the presence and localization of Ce in the spent fuel.

scholarly journals BOUNDARY CONDITION MODELING EFFECT ON THE SPENT FUEL CHARACTERIZATION AND FINAL DECAY HEAT PREDICTION FROM A PWR ASSEMBLY

2021 ◽  
Vol 247 ◽  
pp. 12008
Author(s):  
Augusto Hernandez-Solis ◽  
Klemen Ambrožič ◽  
Dušan Čalič ◽  
Luca Fiorito ◽  
Bor Kos ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Fuel Assembly ◽  
Emission Rate ◽  
Neutron Emission ◽  
Spent Fuel ◽  
Decay Heat ◽  
Fuel Pin ◽  
Condition Modeling ◽  
Fuel Characterization ◽  
Relative Differences

In this paper, two main exercises have been carried out to describe the effect that varying an albedo boundary condition has in the computation of observables such as decay heat, neutron emission rate and nuclide inventory from a PWR fuel assembly (or a configuration of assemblies) during a depletion scenario. The SERPENT2 code was then employed to emphasize the importance of modeling a proper boundary condition for such purposes. Moreover, the effect of taking into account more than a single fuel-pin region for depletion studies while varying the type of boundary condition, was also accounted for. The first exercise has the main objective of comparing in a single fuel assembly the albedo variations ranging from 1.1 up to full vacuum conditions. By comparing to the reference assembly (considered to be the case of full reflective conditions), relative differences up to +17% were observed in decay heat and up to almost -30% in neutron emissions. Also, a clear dependence on the albedo was detected if more than one depletable zone was considered while computing the integral value of observables of interest. Regarding the second exercise, where a 3 × 3 configuration of fuel assemblies is being now considered with a reflector section in the middle, a negligible effect on the observables was observed for the single fuel pin zone case; instead, an effect in the 244Cm computation when analyzing two fuel pin-zones produced a change in the neutron emission rate during cooling time up to 2.5% (while comparing it to the reference single assembly case).

Nuclear forensic applications of uranium oxide chemistry and morphology

2015 ◽  
Author(s):  
◽  
Alison Louise Tamasi
Keyword(s):  
Uranium Oxide ◽  
Fuel Cycle ◽  
Raw Materials ◽  
Spent Fuel ◽  
Sem Images ◽  
University Of Missouri ◽  
X Ray ◽  
Chemical Signatures ◽  
History Of ◽  
The Stability

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] The entire nuclear fuel cycle is a chemistry-intensive process, from accessing the raw materials from ore, to enriching and forming the fuels, to the eventual long-term disposition or reprocessing of the spent fuel. This chemistry is vital to nuclear forensics, as the chemical history of a sample imbues it with unique signatures that should provide insight into the processing and conversion a sample has undergone. Of course, now that many countries have had nuclear programs for decades, it is appropriate to question the stability of these chemical signatures. This necessitates the assessment of what new chemical and morphological signatures are introduced by the aging in bulk uranium oxide samples, and whether those signatures can be used to elucidate the conditions under which the materials were stored. This thesis is concerned with the analysis of uranium oxide samples: both high-purity UO2, alpha-U3O8, and alpha-UO3 samples, and several legacy U3O8 and UO3 samples. The samples were aged over several years in chambers designed to control temperature and relative humidity. There are two primary focuses for analysis of these aged uranium oxides -- the first is the identification of chemical signatures using powder X-ray diffraction (p-XRD) and extended X-ray absorption fine structure (EXAFS) analysis, and the second is the identification of morphological signatures contained in scanning electron microscopy (SEM) images using a standardized lexicon for consistent textural analysis. LA-UR-15-26762.

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